Pretreatment of dyeable polyolefins

ABSTRACT

THIS INVENTION PROVIDES A METHOD FOR TREATING A DYEABLE POLYOLEFIN FIBER BEFORE A DYEING STEP, WHICH COMPRISES CONTACTING THE DYEABLE POLYOLEFIN FIBER WITH A SPECIFIC LIQUID TREATING FLUID. THE FLUID CONSISTS ESSENTIALLY OF 100 PARTS BY WEIGHT MADE UP AS FOLLOWS: FROM 98 TO 80 PARTS BY WEIGHT OF ACETIC ACID HAVING A CONCENTRATION FROM 40 WEIGHT PERCENT AQUEOUS TO GLACIAL, AND FROM 2 TO 20 PARTS BY WEIGHT OF AN ACID CHOSEN FROM THE GROUP CONSISTING OF SUBSTANTIALLY WATER INSOLUBLE C8 TO C12 ALKANOIC ACIDS. THE TREATING CONDITIONS INCLUDE A PRESSURE SUFFICIENT TO MAINTAIN THE TREATING FLUID IN THE LIQUID PHASE, A TEMPERATURE FROM ABOUT 75*F. TO ABOUT 175*F. AND A TREATING TIME FROM ABOUT 1 MINUTE TO ABOUT 5 MINUTES. SUITABLY, THE TREATING STEP IS FOLLOWED BY CONVENTIONAL ACID DYEING.

' 3 594 114 PRETREATMENT F DSZEABLE POLYOLEFINS Albert J. Shmidl andLeroy C. Jennings, Baytown, Tex., assignors to Esso Research andEngineering Company No Drawing. Filed Sept. 30, 196 Ser. No. 583,475Int. Cl. D0611 5/00 US. Cl. 8-468 13 Claims ABSTRACT OF THE DISCLOSUREThis invention provides a method for treating a dyeable polyolefin fiber[before a dyeing step, which comprises contacting the dyeable polyolefinfiber with a specific liquid treating fluid. The fluid consistsessentially of 100 parts by weight'made up as follows: from 98 to 80parts by weight of acetic acid having a concentration from 40 weightpercent aqueous to glacial, and from 2 to 20 parts by weight of an acidchosen from the group consisting of substantially water insoluble C to Calkanoic acids. The treating conditions include a pressure sufficient tomaintain the treating fluid in the liquid phase, a temperature fromabout 75 F. to about 175 F., and a treating time from about 1 minute toabout 5 minutes. Suitably, the treating step is followed by conventionalacid dyeing.

The present invention is directed to an improvement in the art of dyeingpolyolefins. More particularly, the present invention is directed to apretreating step whereby polyolefins which contain basic nitrogendyesites are given enhanced characteristics for dyeing with acid-typedyes.

Polyolefin fibers (such as polypropylene) which contain basic nitrogendyesites (such as are provided by polyvinylpyridine) are quite easilydyed with dispersed-type dyes. The fibers are not readily dyed however,with acidtype dyes, which, because of their good stability againstfading in sunlight, are preferred for many uses.

Dyeable polyolefins have been pretreated with Lewis acids to enhancetheir dyeability with acid-type dyes. Glacial acetic acid has beenemployed for this purpose. As will be seen hereinafter, the presentinvention is an improvement over that process (described in the US.Rubber South African application 62/5464). The present process makesmore practicable the use of dyeable polyolefins as synthetic fibers.

One of the objectives of the polyolefin industry has been to produce afiber which is susceptible to treatment in the same manner as competingfibers When used in woven goods. Polyolefin fibers have a number ofadvantages over the natural fibers, including a resistance to moistureand mildew which cannot be obtained in wool or natural fibers. However,polyolefins suffer from one major drawback; that is, the polyolefin(such as polypropylene) is a hydrocarbon and does not contain a dyesitewhich is susceptible of reaction with a dye. Thus, the prior art hasutilized a practice of compounding the fibers With colored pigmentfillers, or dyeing the polyolefin by dissolving a coloring agent intothe amorphous regions of the polymer. Neither expedient has beenentirely successful.

In the commercial practice of using dyeable fibers such as wool, naturalfibers, etc., the raw fibers are usually spun and woven before beingsubmitted to a dyebath, so that a woven fabric is first obtained priorto dyeing. If the results of the dyebath are unsatisfactory for anyreason, the fabric can be bleached and redyed by the manufacturer. Thepreviously used blends of polypropylene with pigments are notsusceptible to bleaching, and the polypropylene containing dissolveddyes is not resistant to leaching during laundering.

If polyolefins are to compete in the market with natural and syntheticfibers, they must be prepared in a United States Patent 0 3,594,114Patented July 20., 1971 manner which allows them to be dyed and bleachedin a manner analogous to the treatment of the natural fibers. Thepreparation of a polyolefin which contains basic nitrogen dyesites hasbeen suggested. First, dyesites can be incorporated by copolymerizationof a vinyl compound (having a basic nitrogen substituent) with theolefin monomer in order to incorporate the dyesite into the structure ofeach polymer chain. A second manner in which the dyesite can beincorporated is by physically blending with the homopolymer a materialwhich does contain dyesites. For example, small amounts of apolyvinylpyridine can be blended into the homopolymer. A third manner ofincorporating dyesites within the polyolefin fiber is by a graftpolymerization, such as the polymerization of styrene and a maleicanhydride upon the chain of a polypropylene homopolymer. It has alsobeen suggested that polyvinylpyridine can be engrafted upon the chain ofa polypropylene homopolymer.

The net result of all of these attempts to introduce reactive dyesitesinto the polyolefin itself is to distribute basic nitrogen dyesitesthroughout the polymer. When the polymer is drawn into a fiber, thisresults in a distribution of at least a part of the dyesites at or nearthe surface of the fiber. From the standpoint of economics, it isusually desirable to keep the amount of the added dyesites :at apractical minimum. Where the basic nitrogen dyesite is employed, it isusually employed in amounts within the range from 0.05 to 0.5 weightpercent of nitrogen, based on the weight of the entire polymer. Nitrogenlevels above 0.5 weight percent can be used, but are not as economicallyattractive as the lower levels, and in some cases can result in animpairment of the physical property of the resulting fibers.

At the low concentrations of basic nitrogen dyesites which are employed,there is a real problem involved in attempting to reach the dyesiteswith the dye in the aqueous dyebath which is employed. Only a smallportion of the dyesites would appear at the surface of the fiber, andthose which are internal of the fiber cannot be contacted unless the dyeitself penetrates into the fiber. This presents problems of unevendyeing, resulting in barr 0r spotted appearance of the resulting fabric.

It has been suggested by US. Rubber in its South African application62/5464 that a polyolefin blended with polyvinylpyridine can bepretreated by reaction with a Lewis acid before introduction into thedyebath. This activates the polymer for reaction with acid-type dyes.The US. Rubber application suggests the use of a number of widelydifferent Lewis acids, among which are organocarboXylic acids, such asformic, acetic, propionic and other alkanoic acids in the C to C range,as well as stearic, undecylenic, oleic, benzoic, etc., acids. Theseacids are suggested for use as such or in a water solution containing atleast 20% concentration of the acids. The fiber or fabric is firsttreated with the acid solution, and is thereafter introduced into thedyebath.

Although the pretreatment process suggested by US. Rubber results in animproved dyeing of the fabric, the use of concentrated acids (such asglacial acetic acid) leaches additives (e.g., antioxidants) from thefibers, while the use of dilute acids has been, in general,unsatisfactory. The present invention allows the use of dilute aceticacid and lower temperatures in accomplishing a commercially acceptabledyeing process.

Before proceeding to a specific discussion of the manner in which thepresent invention is carried out, it should be understood that thefollowing terms wherever used in the present application have themeanings set forth below:

The term fiber shall mean a filament, drawn or 11ndrawn, in the form ofdiscrete filaments, yarn, or woven fabric material.

The term polyolefin shall mean a solid hydrocarbon polymer, stabilizedor unstabilized, containing poly-m-olefins, such as polyethylene,polypropylene, polyisobutene, poly-l-butene, etc.; polydiolefins, suchas poly-1,4-butadiene, etc.; and other polymers, such as polystyrene,etc., either as the homopolymer, as a blend of homopolymers (forexample, polyethylene and polypropylene or polypropylene andpolyisobutene), or as an olefinic copolymer, such as ethylene-propylenerandom copolymer, ethylenepropylene block copolymer, etc., includingethylene-propylene rubber. When reacted or blended with a materialcontaining basic nitrogen dyesites, the material is referred to as adyeable polyolefin.

The term dyesides refers to reactive portions incorporated into thepolymer which aid in retaining the dye to be used, and is preferably anamino nitrogen, and (as applied to the present invention) in all 'caseswill be a basic nitrogen.

The term dyesite additive refers to a material containing dyesites whichis blended with a polyolefin in order to provide dyesites.

The term acid-type dye is to be considered to include both the acid dyesand the premetallized dyes which fall under the usual definition of anacid-type dye: a dye which will dye wool from an acid bath.

TYPES OF DYEABLE POLYOLEFINS The polyolefins to which the presentinvention is particularly directed are those which basically containonly hydrogen and carbon, such as polyethylene, polypropylene,ethylene-propylene copolymers, polyisobutene, polyisoprene, etc. Assuch, they contain no dyesites and cannot be successfully dyed. Dyesitesmay be chemically incorporated into the polyolefins by copolymerizingthe olefin monomers with small amounts of dyesite-containing monomers;that is (using polypropylene as an example), both propylene and adyesite-containing monomer (such as an alkenyl amine) may be introducedinto the polymerization zone to obtain a polymer which has dyesites as apart of the polymer structure. This type of dyeable polypropylene isexemplified by a propylene-N,N-diisopropyl- 7-octenylamine copolymercontaining 0.06 weight percent nitrogen.

Alternatively, the dyesite-containing monomer may be grafted onto thepolypropylene after polymerization, as exemplified by polypropylene withpolyvinylpyridine engrafted thereupon.

Other variants include physical blends of polymers (such aspolypropylene) with materials containing dyesites, such as copolymerscontaining reactive dyesites in the chain (similar to the octenylamine-propylene polymer described above) or with other organic orinorganic materials which provide such dyesites (such aspolyvinylpyridine). The relative proportions in these blends will dependon a balancing of a number of factors, including the effect of the blendstock on polymer properties, intensity of color required, efficiency ofdyesite additive, etc. The particular additive to be used will depend onthe type of dye to be employed, the use to which the dyed material willbe put, etc.

All of these modified fibers are referred to herein as dyeablepolyolefins. The process of the present invention is equally applicableto films and fibers, drawn and undrawn, woven and unwoven, which aremade from resins of the dyeable polyolefins.

ACID DYES The present invention contemplates the use of acidtype dyes.As used in this application, the acid-type dye will include thepremetallized dyes. As examples of the dyes that are useful in thisprocess, and as incorporated in the dyeing composition, are thefollowing dyes as set forth in Table I. The color index, whereavailable, is shown in parentheses.

4 TABLE I Dye Acid dyes:

Erio Anthracene Rubine 3 GP-(Acid Red 57). Erio Fast Violet LN--(61700).Erio Anthracene Brilliant Blue 2 GC(62055). Erio Fast Brown 5 RLDuronylan Scarlet LVGGL Duronylan Brilliant Blue LVGF Duronylan BlackLVTRR Irganol Scarlet RLS Alizarine Light Green GSN(Acid brown 25;61570). Wool FastBlue HFL(AB25). Premetallized dyes: I

Levalan Navy Blue IRL Levalan Olive I-GL Irganol Brilliant Yellow 3GLS(AY 127). Irgalan Violet 5 RL Chromolan Orange R Chromolan BlackNWA-(Acid Black 52;l57ll). Vialon Fast Yellow G(HY 118). Vialon Fast RedB(AR 225). Vialon Fast Violet B Vialon Fast Green FFG Vialon Fast FFGVialon Fast Brown R Vialon Fast Blue Grey B-(AB61). Vialon Fast Red GVialon Fast Violet RR Vialon Fast Black -R-(AB63). Avilan Fast Scarlet 2R Avilan Fast Navy Blue BW Avilan Fast Black B Avilan Fast Red GW AvilanFast Violet 3B Avilan Fast Navy Blue R Avilan Fast 'Olive GW Lanamid RedGL Lanamid Blue BL Lanamid Dark Green Lanamid Brown BL-(AB-l9). LanamidBordeaux BL Isolan Red 2G Isolan Black BGL Irgalan Violet 5RL IrgalanBlue RL Irgalan Brilliant Green 3GL Irgalan Dark Brown SR Lanasyn DarkViolet RL Lanasyn Brown RL Lanasyn Black BGL Lanasyn Yellow ZGW-(AY129). Lanasyn Brilliant Blue GL Lanasyn Olive 2GL Cibalan Blue BRLAtalan Red 2GA Atalan Blue GA Vitrolan Bordeaux RM Ortalan Violet BOrtalan Black G Special Capracyl Blue G Neolan Blue 2G-(AB 158;l4880).Neolan Green 8G(Acid Green 24). Neolan Brown GR Sandolan Dark Brown GLAs can be seen by reference to the above table, the present inventioninvolves the use of acid and premetallized dyes to obtain a moreeffective dyeing of dyeable polyolefins.

In using the dye, it is employed generally in accordance withinstructions provided by the manufacturer. Generally, the dyes will beused in suspension or in solution in a hot aqueous dyebath. Thepremetallized dyes are employed in an aqueous dispersion, being in aconcentration of 1.0 to 5.0 weight percent O.W.F. (that is, based on theweight of the fiber to be dyed in the dyebath). A dispersing agent canbe employed as hereinafter described, preferably being added to thedyebath in an admixture with the treating acid. The dyebath is kept at atemperature of 100 to 212 F., and the fabric is contacted with thedyebath for a period of time determined by the type of fiber employed inthe fabric, type of dye employed, the depth of color desired, dyeconcentration, etc. The pH in the dyebath will vary, depending on theparticular dye being employed and the desire of the dyer. The pH may beadjusted by adding a C to C alkanoic acid, or a dilute mineral acid suchas sulfuric acid, either at the beginning of the dyeing process insuflicient quantities to maintain the pH at the desired level, or bygradual addition during the conduct of the dyeing process. For low pHdyeing, the use of formic acid is preferred, since it is possible toobtain a pH of 3.0 while using 3% formic acid (based on the weight ofthe fiber) as compared to about a 3.5 pH when employing similar amountsof acetic acid.

PRETREATING FLUID The present invention contemplates the use of a novelpretreating fluid. This fluid is made up of two constituents: (1) awater-soluble acid (acetic acid) and (2) a substantially water-insolubleacid such as octanoic acid. This treating fluid allows the treatment offibers to be accomplished at lower temperatures or with dilute (ratherthan glacial) acetic acid, thus minimizing the extraction from the fiberof constituents added to the polyolefin for inhibition of oxidation,etc.

The treating fluid can be made up of acetic acid having a concentrationfrom. 40% aqueous to glacial. This acetic acid can be mixed with from 2to 20 weight percent (based on the resulting mixture) of a C to Csubstantially water-insoluble alkanoic acid (or substituted derivativethereof). Above 15 weight percent, there is no appreciable improvement.Suitable alkanoic acids are hexanoic, heptanoic, octanoic, nonanoic,decanoic, undecanoic, and dodecanoic acids, and the isomers thereof.Using octanoic acid as an example, the treating fluid might have thefollowing formulations:

Parts by Weight Glacial acetic acid 90 Octanoic acid 10 Parts by weight40 wt. percent aqueous acetic acid 90 Octanoic acid 10 THE METHOD OFPRETREATING A dyeable polyolefin fiber, e.g. in a woven fabric, iscontacted with the treating fluid by immersion or by spraying. The fiberis maintained in contact with the treating fluid for a period of fromabout 1 minute to about minutes, at a temperature from about 75 F. toabout 175 F., and a pressure from 0 p.s.i.g. to 25 p.s.i.g. (preferably,by immersion for about 2 minutes at 140 F., atmospheric pressure).Pressure is not critical, so long as the treating fluid is maintained inthe liquid phase. The preferred treating fluid, for use under preferredconditions, will be made up of about 90 parts by weight of 40% aqueousacetic acid and parts by Weight of octanoic acid.

After pretreatment, the fiber is removed from contact with the treatingfluid and is dyed in the regular manner with an acid-type dye. Excesstreating fluid may be removed from the fibers by sponging or by allowingthe fibers to drip-dry, if desired. The fibers may, however, be placedin the dyebath without a deliberate attempt to remove the excess fluidif the resulting loss of fluid is not uneconomical.

6 DYEING The dyeing step is carried out as usual. Normally, the specificconditions are recommended by the manufacturer of the dye which isemployed. In general, dyeing conditions will include a dyebath made upas follows:

Water: 20-50 (preferably 30) parts/ part of fiber Dye: 1-5 wt. percent(preferably 3 wt. percent) O.W.F.

Dispersant: 0.5-1 wt. percent (preferably 0.5 wt. percent) O.W.F.

pH: 2.7 to 5.0 (preferably 3.7)

The temperature is usually from 200 to 212 F. (preferably 208 F.) andthe pressure is usually atmospheric. The dyeing time (measured from thetime the dyebath reaches the dyeing temperature) may be from 20 to 90minutes, preferably about 30 minutes.

The dyebath is first made up, then the fiber is introduced. The dyebathis then heated, under mild agitation or fluid circulation, to the dyeingtemperature. After the dye has been absorbed by the fiber, the fiber isremoved from the dyebath, scoured, and dried.

EXAMPLES In the following examples, 99 parts of polypropylene (meltindex 12) were blended with about 1 part of a polyvinylpyridinecopolymer derived from equimolar parts of 2-methyl-5-vinylpyridine and2-vinylpyridine, having a molecular weight of about 40,000. The blendcontained about 0.15 weight percent nitrogen based on the weight of theentire blend.

Example 1 The fiber was treated at atmospheric pressure by immersion for2 minutes in glacial acetic acid at 140 F. This fiber dyed to a fairblue with 2% O.W.F. Erio Anthracene Brilliant Blue 2GC, an acid dye.

Example 2 The fiber was treated at 140 F. and atmospheric pressure byimmerision for 2 minutes in an admixture of 90 parts of glacial aceticacid and 10 parts of octanoic acid. This fiber dyed to about three timesthe color intensity of that shown in Example 1 when dyed under the samedyeing conditions with the Eric Anthracene Brilliant Blue 2GC.

Example 3 The fiber was treated with the admixture of acids as inExample 2 for 2 minutes at room temperature (about F.). It showed moredye receptivity for the same blue acid dye than the fiber of Example 1.

Example 4 The fiber was treated with an admixture of 86 parts of 50%aqueous acetic acid and 14 parts of octanoic acid, under the sameconditions as Example 1, and was then dyed with a premetallized dye.Vialon Fast Violet RR. The sample showed a deeper color uptake than acompanion sample treated with glacial acetic acid under the conditionsof Example 1.

The various test samples are shown in color in the atached aflidavitunder Rule 132, which is hereby incorporated by reference into thisdisclosure.

Having disclosed our invention, and the preferred mode and embodimentthereof, we claim:

1. A method of treating a dyeable fiber consisting essentially' of ablend of a polyvinylpyridine in a poly-w olefin in an amount suflicientto provide between 0.05 to 0.5 weight percent nitrogen, based on theWeight of the entire blend, which comprises in a treating zone,contacting said dyeable fiber with a liquid treating fluid prior todyeing of said fiber, said treating fluid consisting essentially of 100parts by weight as follows:

from 98 to parts .by weight of acetic acid having a concentration from40 weight percent aqueous to glacial, and

7 from 2 to 20 parts by weight of an acid chosen from the groupconsisting of substantially waterinsoluble C to C alkanoic acids undertreating conditions including a pressure suificient to maintain thetreating fluid in the liquid phase, a temperature from about 75 F. toabout 175 F., and a treating time from about 1 minute to about 5minutes.

2. A method in accordance with claim 1 wherein the alkanoic acid isoctanoic acid.

3. A method in accordance with claim 1 wherein the alkanoic acid isisodecanoic acid.

4.. A method in accordance with claim 2 wherein the constituents are asfollows:

90 parts by weight of glacial acetic acid and parts by weight ofoctanoic acid.

5. A method in accordance with claim 2 wherein the constituents are asfollows:

90 parts by weight of 40 weight percent aqueous :acetic acid and 10parts by weight of octanoic acid.

6. A method in accordance with claim 2 wherein the constituents are asfollows:

86 parts by weight of 50 weight percent aqueous acetic acid and 14 partsby weight of octanoic acid.

7. A method of dyeing a dyeable fiber consisting essentially of a blendof a polyvinylpyridine in a poly-aolefin in an amount suflicient toprovide between 0.05 and 0.5 weight percent nitrogen, based on theweight of the entire blend, which comprises in a treating zone,contacting said dyeable fiber with a liquid treating fluid, saidtreating fluid consisting essentially of 100 parts by weight, asfollows:

from 98 to 80 parts by weight of acetic acid having a concentration from40 weight percent aqueous to glacial, and from 2 to 20 parts by weightof a substantially water-insoluble C to C alkanoic acid under treatingconditions including a pressure sufficient to maintain the treatingfluid in the liquid phase, a temperature from about 75 F. to about 175F., and a treating time from about 1 minute to about 5 minutes,

separating the resulting treated fiber from said treating thereafter ina dyeing zone, under dyeing conditions, contacting said treated fiberwith an acid-type dye in an aqueous dyebath,

said aqueous dyeabth containing from 1 to 5 weight percent O.W.F. ofacid dye, from 0.5 to 1 weight percent of a dispersant, and

said dyeing conditions including a pressure sufficient to maintain thedyebath in the liquid phase,

a temperature from 200 to 212 F.,

a pH from 2.7 to 5.0, and

a dyeing time from 20 to 90 minutes.

8. A method in accordance with claim 7 wherein the alkanoic acid isoctanoic acid.

9. A method inaccordance with claim 7 wherein the alkanoic acid isisodecanoic acid.

10. A method of treating a dyeable fiber, said fiber consisting of from0.5 to 3 weight percent polyvinylpyridine blended into polypropylene,which comprises in a treating zone, contacting said dyeable fiber with aliquid treating fluid prior to dyeing of said fiber,

said treating fluid consisting essentially of 100 parts by Weight, asfollows:

from to 86 parts by weight of acetic acid having a concentration from 40weight percent aqueous to glacial, and

from 10 to 14 parts by weight of an acid chosen from the groupconsisting of octanoic acid and isodecanoic acid under treating.conditions including a pressure suflicient to maintain the treatingfluid in the liquid phase, a temperature from about 75 F. to about 175F., and a treating time from about 1 minute to about 5 minutes.

11. A method in accordance with claim 10 wherein the acid is octanoicacid.

12. A method of dyeing a dyeable fiber, said fiber consisting of from0.5 to 3 weight percent polyvinylpyridine blended into polypropylene,which comprises in a treating zone, contacting said dyeable fiber with aliquid treating fluid,

said treating fluid consisting essentially of parts by weight, asfollows:

from 90 to 86 parts by weight of acetic acid having a concentration from40 Weight percent aqueous to glacial, and

from 10 to 14 parts by weight of an acid chosen from the groupconsisting of octanoic acid and isodecanoic acid under treatingconditions including a pressure sufficient to maintain the treatingfluid in the liquid phase,

a temperature from about 75 F. to about F., and

a treating time from about 1 minute to about 5 minutes,

separating the resulting treater fiber from said treated thereafter in adyeing zone, under dyeing conditions,

contacting said treated fiber with an acid-type dye in an aqueousdyebath,

said aqueous dyebath containing from 1 to 5 weight percent O.W.F. ofacid dye,

from 0.5 to 1 weight percent O.W.F. of a dispersant,

a pH from 2.7 to 5.0, adjusted by addition of an acid chosen from thegroup consisting of formic acid, acetic acid, and sulfuric acid, and

said dyeing conditions including a pressure suflicient to maintain thedyebath in the liquid phase,

a temperature from 2000 to 212 F., and

a dyeing time from 20 to 90 minutes.

13. A method in accordance with claim 12 wherein the acid is octanoicacid.

References Cited UNITED STATES PATENTS 3,231,530 l/1966 Prahl 8-553,361,843 l/1968 Miller et 'al. 260-895 FOREIGN PATENTS 1,388,25312/1964 France 8-55 752,759 2/ 1967 Canada.

OTHER REFERENCES K. S. Markley: Fatty Acids, Interscience Pub., N.Y.,1960, pp. 609, 633, '639, 647.

NORMAN G. T ORCHIN, Primary Examiner C. L. BOWERS, JR., AssistantExaminer US. Cl. X.R. 8-3l, 42, 100

